哈希表實例程序（C語言）

下面是 C語言哈希表實例程序：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>

#define SIZE 20

struct DataItem {
int data;
int key;
};

struct DataItem* hashArray[SIZE];
struct DataItem* dummyItem;
struct DataItem* item;

int hashCode(int key){
return key % SIZE;
}

struct DataItem *search(int key){
//get the hash
int hashIndex = hashCode(key);

//move in array until an empty
while(hashArray[hashIndex] != NULL){
if(hashArray[hashIndex]->key == key)
return hashArray[hashIndex];

  //go to next cell
  ++hashIndex;

  //wrap around the table
  hashIndex %= SIZE;

}
return NULL;
}

void insert(int key,int data){
struct DataItem *item = (struct DataItem*) malloc(sizeof(struct DataItem));
item->data = data;
item->key = key;

//get the hash
int hashIndex = hashCode(key);

//move in array until an empty or deleted cell
while(hashArray[hashIndex] != NULL && hashArray[hashIndex]->key != -1){
//go to next cell
++hashIndex;

  //wrap around the table
  hashIndex %= SIZE;

}
hashArray[hashIndex] = item;
}

struct DataItem* delete(struct DataItem* item){
int key = item->key;

//get the hash
int hashIndex = hashCode(key);

//move in array until an empty
while(hashArray[hashIndex] != NULL){

  if(hashArray\[hashIndex\]->key == key){
     struct DataItem\* temp = hashArray\[hashIndex\]; 

     //assign a dummy item at deleted position
     hashArray\[hashIndex\] = dummyItem; 
     return temp;
  }

  //go to next cell
  ++hashIndex;

  //wrap around the table
  hashIndex %= SIZE;

}
return NULL;
}
// 顯示所示數據項
void display(){
int i = 0;

for(i = 0; i<SIZE; i++) {
if(hashArray[i] != NULL)
printf(" (%d,%d)",hashArray[i]->key,hashArray[i]->data);
else
printf(" ~~ ");
}

printf("\n");
}

int main(){

dummyItem = (struct DataItem*) malloc(sizeof(struct DataItem));
dummyItem->data = -1;
dummyItem->key = -1;

insert(1, 20);
insert(2, 70);
insert(42, 80);
insert(4, 25);
insert(12, 44);
insert(14, 32);
insert(17, 11);
insert(13, 78);
insert(37, 97);

display();

item = search(37);

if(item != NULL){
printf("Element found: %d\n", item->data);
}else{
printf("Element not found\n");
}

delete(item);

item = search(37);

if(item != NULL){
printf("Element found: %d\n", item->data);
}else{
printf("Element not found\n");
}
}

如果我們編譯並運行上述程序那麼這將產生以下結果 -

~~ (1,20) (2,70) (42,80) (4,25) ~~ ~~ ~~ ~~ ~~ ~~ ~~ (12,44) (13,78) (14,32) ~~ ~~ (17,11) (37,97) ~~
Element found: 97
Element not found

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